The present invention relates to a locking mechanism for a roll-off container hoist, and more particularly, to a locking mechanism for securing a roll-off container to the roll-off container hoist when the hoist is in a transport orientation and for releasing the roll-off container when the hoist is moved from the transport orientation toward a hoisting orientation. The present invention also relates to a container hoist which includes such a locking mechanism, as well as a vehicle which carries a locking-mechanism-equipped container hoist. The present invention also provides a method of using the container hoist.
Vehicle-mounted container hoists are commonly used to load, unload and transport roll-off containers. Examples of such roll-off containers include conventional trash compactors and receptacles associated therewith. Such roll-off containers can weigh thousands, of pounds. It is therefore extremely important that such containers remain secured to the vehicle and/or hoist during transport. Failure to keep the container secured during transport can pose a significant danger to the driver of the vehicle, as well as the public.
During transport, the roll-off containers are subject to significant jarring forces generated by changes in the vehicle's acceleration, abrupt steering, rapid braking, pot holes, and otherwise uneven road surfaces. There is consequently a need for a reliable and strong locking arrangement which positively secures the container to the vehicle and/or hoist.
Although simple manual locking arrangements can be used to secure the roll-off container to the vehicle, such manual arrangements disadvantageously depend upon the operator's memory. If the operator forgets to lock the container to the vehicle or to the hoist, a significant safety hazard will exist. Manual locking arrangements therefore provide less than optimum results.
In order to avoid the risk of having the operator forget to engage the locking mechanism, complex automatic locking arrangements can be used. Such locking mechanisms might include sensors which detect some aspect of the hoisting operation or the presence of the container, and a lock driver responsive to the sensor to actuate a locking device. Alternatively, such arrangements may include a spring or other resilient member which urges a locking member to engage the container and which is selectively disengaged to release the container using complex disengagement means. The resulting arrangements, however, can be relatively expensive to implement. In addition, they may be susceptable to failure, especially when exposed to wet and/or dusty environments, as well as road debris.
With regard to the spring or resilient member-based arrangements, it is possible for the spring or resilient member to become damaged by the weight of the containers. Moreover, the containers are sometimes transported in an empty condition, but are also transported when full. There are consequently significant variations in the weight of the containers. This makes it extremely difficult to obtain a spring arrangement that reliably locks and disengages at the appropriate times.
There is consequently a need in the relevant art for a reliable, simple and inexpensive locking mechanism for use in a roll-off container hoist.